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Nega i e e ec o zinc compounds on hyd a ion kine ics o
o dina y Po land cemen
L Ma ejka1, P Sile 1, R No o ny1, J S ec1, J Masilko1 and F Soukal1
1 B no Uni e si y o Technology, Facul y o Chemis y, Ins i u e o Ma e ials
Chemis y, Pu kyno a 464/118, 612 00 B no, Czech Republic
Email: xcma ejkal@ u b .cz
Abs ac . Me als and me al con aining compounds ha e signi ican e ec on cemen hyd a ion
mechanism and kine ics. The ecycling o was e ma e ials leads o inc ease o con en o me als
in a ious indus ial p oduc s and isibly a ec s p ope ies o he Po land cemen . One
o he me als ha has been known o d as ically inc ease he se ing ime is zinc. Zinc o ms
a ious hyd oxyl species wi h calcium ca ions. Po e solu ion hus has lowe ed concen a ion
o calcium which supp esses o ma ion o po landi e. Due o insu icien concen a ion
o calcium he o ma ion o CSH gel and u he hyd a ion o clinke g ains is inhibi ed The aim
o his s udy is o quan i y he nega i e e ec s o zinc a di e en concen a ions a ambien
empe a u e a 20°C. Isope ibolic calo ime y was used o measu e he nega i e e ec s o zinc
on hyd a ion kine ics o o dina y Po land cemen . Zinc was added o he cemen in he o m
o wo soluble sal s Zn(NO3)2 hyd a e, ZnCl2 and a poo ly soluble compound ZnO.
The concen a ion o zinc added was chosen be ween 0.1 and 1 w . % o clinke . Signi ican
e a da ion o cemen hyd a ion wi h inc easing zinc con en was p o en.
1. In oduc ion
Po land cemen is a hyd aulic binde p oduced by bu ning o g ound limes one, clay and o he aw
ma e ials in o a y kiln. C ea ed clinke is g ound up and mixed wi h small amoun s o gypsum.
P oduced clinke consis o many phases. The main clinke phases a e icalcium silica e (abb . C3S–
3CaO·SiO2 o Ca3SiO5, ali e), dicalcium silica e (abb . C2S–2CaO·SiO2 o Ca2SiO4, beli e), icalcium
alumina e (abb . C3A–3CaO·Al2O3 o Ca3Al2O6, celi e) and calcium alumino e i e (abb . C4AF–
4CaO·Al2O3·Fe2O3 o Ca4Al2Fe2O10, b ownmille i e) [1].
Va ious me als can be in oduced in o cemen in all s ages o p oduc ion o applica ion. Limes one
based on he speci ic deposi ends o con ain o he mine als such as sphale i e (ZnS). O dina y Po land
cemen is also widely esea ched as a binde o solidi ica ion and immobiliza ion o oxic was e
con aining me als. Solidi ica ion and immobiliza ion o oxic elemen s encompasses educing
bioa ailabili y, leachabili y, and mobili y o haza dous elemen s [1‒5].
Zinc can be p esen in admix u es, in i s own sepa a e phase in clinke o in solid solu ion wi h main
clinke phases. Solid solu ion wi h C3S seems o be p e e ed o e C2S [6]. Ions o zinc p esen in po e
solu ion hyd olyse in o a ious hyd oxyl species. These compounds coa hyd a ing g ains o cemen
clinke and eac wi h calcium ca ions e ol ed in o he po e solu ion du ing o ma ion o CSH gel.
The esul ing insoluble Ca(Zn(OH)3)2·2 H2O deple es concen a ion o Ca2+ p e en ing he o ma ion
o po landi e and se e ely supp essing sa u a ion o po e solu ion and u he hyd a ion o cemen
g ains. P ecipi a ion o po landi e and CSH gel is inhibi ed un il all zinc has been con e ed in o
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insoluble Ca(Zn(OH)3)2·2H2O. Once his p ocess eaches comple ion hyd a ion con inues once mo e.
Reac ions leading o Ca(Zn(OH)3)2·2 H2O a e shown in equa ions (1) and (2) [7‒10].
ZnO + H2O + 2 OH−→Zn(OH)4
2− (1)
2 Zn(OH)4
2− + Ca2+ + 2 H2O → Ca(Zn(OH)3)2∙ 2 H2O + 2 OH− (2)
The pu pose o his s udy is o show he e ec o zinc compounds ZnCl2, Zn(NO3)∙6 H2O and poo ly
soluble compound ZnO a di e en concen a ions on he hyd a ion induc ion pe iod o o dina y
Po land cemen a lowe ambien empe a u e han mos s udies and compa e esul s wi h s udies using
highe ambien empe a u e. Exposu e o zinc oxide o humidi y a ec s bo h solubili y and pa icle size
dis ibu ion. Mois u e p esen in chemicals can lead o misleading esul s by al e ing he concen a ion
o zinc in he zinc sou ce. These pa ame e s can also a ec eac ion kine ics o zinc oxide in po e
solu ion. Moni o ing o hese e ec s is done using isope ibolic calo ime y. I is appa en ha ambien
empe a u e has signi ican in luence on bo h hyd a ion o cemen and mechanisms behind zinc induced
p olonging o induc ion pe iods.
2. Expe imen al
2.1. Ma e ials and Sample P epa a ions
All samples we e p epa ed using cemen CEM I 42,5 R p oduced by Mok á—Českomo a ský cemen ,
a.s., Heidelbe g Cemen Czech Republic. Chemical composi ion o his cemen is p o ided in echnical
documen a ion and is shown in able 1 [11]. Each cemen sample con ained a speci ic amoun o zinc
equal o weigh % o cemen (1, 0.5 and 0.1%) and 0.4 wa e o cemen a ion. Cemen pas es we e
p epa ed using s anda d ki chen aid mixe acco ding o he no m ČSN EN 196-1.
Table 1. Chemical composi ion o used cemen [11].
Componen
Cemen (w . %)
CaO
63.7
SiO2
19.6
Al2O3
4.8
Fe2O3
3.3
MgO
1.4
SO3
3.1
Cl-
0.040
K2O
0.75
Na2O
0.19
Insoluble
0.7
LOI
3.4
Zinc was in oduced in o cemen pas e in a o m o soluble sal s ZnCl2 and Zn(NO3)2∙6 H2O and
poo ly soluble compound ZnO in concen a ions 0.1; 0.5 and 1 w . % o pu e zinc in cemen .
The humidi y o he oxide was de e mined wi h Ke n MLS 50-D humidi y analyse . Zinc oxide used as
one o zinc sou ces con ained on a e age 0.35 weigh % o mois u e. ZnO was used in s ock and d ied
o m. ZnO was d ied a 80°C o 72 h. Zinc chlo ide and zinc ni a e hexahyd a e we e pu chased om
Lach-Ne , s. .o. wile zinc oxide was pu chased om Lachema, s. .o..
2.2. Isope ibolic Calo ime y
One o he bes me hods o e alua ing hyd a ion o cemen is mul icell isope ibolic calo ime y. This
ype o de ice allows moni o ing o mul iple samples and e e ences allowing easy compa ison
o di e en cemen mix u es. This me hod is widely used o he s udy o he e ec s o di e en
admix u es such as supe plas icize s, ha dening accele a o s and a ious seconda y indus ial p oduc s
on se ing o cemen pas es [12].
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Cemen mix u es we e weigh ed (300 g) in o polys y ene cup wi h he mocouples and co e ed wi h
he mo-insula ing op. Calo ime ic cu es showing cemen hyd a ion and di e ences be ween a ious
samples we e ob ained using isope ibolic calo ime y in a oom wi h ambien empe a u e a 20°C.
3. Resul s and discussion
Mix u es o samples we e p epa ed ou side o he calo ime e hus he i s peak on hyd a ion cu e was
no measu ed in i s en i e y. Ne e heless, he ea ly s ages o cemen hyd a ion a e no signi ican o his
s udy and do no signi ican ly con ibu e o any changes du ing hyd a ion.
Figu e 1. Isope ibolic calo ime y cu es o samples wi h 1% weigh concen a ion o zinc.
F om calo ime ic cu es shown in igu e 1 i is appa en ha cemen hyd a ion o samples doped
wi h zinc compounds was se e ely inhibi ed as peaks a e shi ed o he igh o he e e ence peak. The e
also appea s o be a small wide peak a a ound 25 h on a cu e o sample wi h zinc ni a e. The hea
e olu ion causing his peak was p obably a esul o dissolu ion o he zinc sal o c ys alliza ion on
he su ace o he cemen g ains as explained in wo ks [13, 14].
Maximum empe a u es eached by sample peaks we e also lowe han ha o e e ence. Maximum
empe a u es eached by he samples we e 32.9°C o cemen wi h chlo ide, 29.9°C o ni a e, 34.0°C
o un ea ed zinc oxide and 33.2°C o samples wi h d ied zinc oxide. This is p obably a esul o zinc
compounds slowing hyd a ion o clinke g ains.
A he same concen a ion o zinc, ZnCl2 seems o show lowe inhibi o y abili y han zinc ni a e.
zinc oxide showed he highes inhibi ion o hyd a ion. The di e ence in beha iou o samples doped
wi h zinc oxide is due o lowe solubili y in wa e han zinc chlo ide and zinc ni a e. Smalle inhibi ion
by chlo ide and ni a e is due o he abili y o chlo ide and ni a e ions o accele a e cemen hyd a ion
wi h chlo ide being mo e e ec i e accele a o a his concen a ion [15].
When compa ed wi h simila s udies done by Šile e al. [16, 17] who used 25°C (as opposed o 20°C
in his s udy) as ambien empe a u e, i s no iceable di e ences a e wide hyd a ion peaks wi h highe
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maximum empe a u e when highe ambien empe a u e is used. This co esponds wi h accele a ed
hyd a ion o cemen and o ma ion o hyd a ion p oduc s. Samples con aining chlo ides show
compa able induc ion pe iod wi h samples in his s udy bu had eached signi ican ly highe maximum
empe a u e a a ound 37 and in con as wi h 32.9°C o ou samples. Maximum empe a u es
o samples wi h zinc oxide a e compa able wi h samples in his s udy bu he leng h o induc ion pe iod
was di e en . This could be explained by lowe solubili y o d ied zinc oxide, bu he di e ence does
no seem o be e y signi ican . In s udy published by Kolářo á e al. [18] hese cemen sys ems we e
s udied using iso he mal calo ime y. Induc ion pe iod measu ed by his me hod was a a ound 80 h
which is e y simila o 77.8 h wi h d ied zinc oxide and 73.3 h wi h un ea ed zinc oxide. Summa y
o de e mined induc ion pe iods is shown in able 2.
Figu e 2. Isope ibolic calo ime y cu es o samples wi h 0.5% weigh concen a ion o zinc.
Beha iou o samples wi h concen a ion o zinc equal o 0.5% o weigh o he clinke isibly
changed as is demons a ed in igu e 2. Peaks belonging o he zinc oxide samples shi ed o he le
indica ing sho e induc ion pe iod. Bo h zinc oxide peaks we e hinne han hose o samples wi h
concen a ion o 1%. This indica es as e hyd a ion ela i e o he p e ious samples.
Peaks o chlo ide and ni a e samples we e isibly hinne han hose o p e ious samples.
The maximum empe a u e eached by ni a e sample was highe han maximum empe a u e
o he e e ence. This indica es accele a ed hyd a ion in compa ison o he samples wi h highe
concen a ion o zinc. Signi ican di e ence was obse ed in induc ion pe iods o ni a e and chlo ide
samples. O e all leng hs o induc ion pe iods o all samples a e in able 2. While he induc ion pe iod
o ni a e sample d opped om 48.2 h o 29 h wi h dec ease in concen a ion o zinc, he induc ion
pe iod o chlo ide sample inc eased om 38.9 h o 56 h wi h dec ease in concen a ion o zinc. This
could be esul o chlo ide and ni a e anions accele a ing hyd a ion h ough di e en mechanisms.
While chlo ide anions a e said o a ec hyd a ion by inco po a ion in o CSH gel, dis up ing i , allowing
mo e wa e o be a ailable o hyd a ion eac ions, ni a es a ec o ma ion o e ingi e and he hyd a ion
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o β-C2S. Nex pa ame e o conside is solubili y o a ious ion species in po e solu ion wi h di e ing
concen a ions o chlo ides and ni a es in such complica ed sys ems [19, 20].
Resul s o Šile [16, 17] measu emen s co esponding o 0.5% chlo ide show highe maximum
empe a u e in compa ison wi h 1% chlo ide, while he induc ion pe iod was simila . In con as wi h
measu emen s in his s udy whe e induc ion pe iod inc eased. This could be explained by loss
o inhibi o y e ec wi h dec easing zinc ion concen a ion, loss o accele a ion by chlo ide ions bu wi h
added accele a ion caused by highe ambien empe a u e. Samples doped wi h ni a es measu ed by
Šile show signi ican inc ease in maximum empe a u e wi h dec ease o concen a ion o ni a e. This
co ela es wi h p esen ed esul s. Al hough sample o 0.5% ni a e measu ed a highe empe a u e
showed sho e induc ion pe iod han ou esul s, he dec ease in induc ion pe iod wi h dec easing
concen a ion was no as high as in ou expe imen . [16, 17].
Figu e 3. Isope ibolic calo ime y cu es o samples wi h 0.1% weigh concen a ion o zinc.
Table 2. Summa y o induc ion pe iods measu ed based on isope ibolic cu es.
Induc ion pe iod (hou )
Concen a ion o zinc (w .%)
ZnCl2
Zn(NO3)2
ZnO un ea ed
ZnO d ied
Cemen
0.0
4.9
0.1
27.1
13.7
14.9
22.6
0.5
56.0
29.0
63.5
56.5
1.0
38.9
48.2
73.3
77.8
Di e ences be ween leng hs o induc ion pe iods and maximum empe a u es eached dec ease wi h
dec easing concen a ion o zinc. Peaks o all samples shi ed o he le indica ing sho e induc ion
pe iods as seen in igu e 3. Samples doped wi h zinc oxide eached highe maximum empe a u e han

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he e e ence cemen . Induc ion pe iods o all samples anged be ween 13.7 h and 27.1 h. These a e
signi ican ly longe induc ion pe iods han he induc ion pe iod o e e ence sample. These esul s a e
compa able wi h li e a u e [16, 17].
Induc ion pe iods measu ed by Kolářo á [18] anged be ween 10 and 20 h. Sample doped wi h zinc
chlo ide had signi ican ly longe induc ion pe iod han hose doped wi h zinc ni a e. This phenomenon
co ela es wi h esul s o Kolářo á. Samples doped wi h zinc oxide had he longes induc ion pe iod ou
o he measu emen s. These esul s a e e y simila o ou measu emen wi h un ea ed zinc oxide
samples. Ou samples o cemen wi h d ied zinc oxide show signi ican ly longe induc ion pe iod han
samples wi h un ea ed oxide.
4. Conclusion
The aim o his s udy was o moni o he e ec s o a ious zinc compounds on induc ion pe iod
o cemen hyd a ion a 20°C ambien empe a u e as opposed o 25°C used in o he s udies [16‒18].
Compounds used as zinc sou ce in his s udy we e soluble sal s ZnCl2 a Zn(NO3)∙6 H2O and insoluble
compound ZnO in d ied and no d ied o m.
• The leng h o induc ion pe iod was inc easing wi h inc easing concen a ion o speci ic zinc
sou ce excep o sample wi h 1 weigh % o zinc in a o m o ZnCl2 due o accele a ion e ec
o chlo ide anions a his concen a ion.
• Ambien empe a u e o 20°C was used du ing measu emen s (as opposed o o 25°C as used in
s udies [16‒18]) which esul ed in signi ican ly highe peak empe a u es eached a high
concen a ions o zinc.
• Di e ences in he leng h o induc ion pe iods be ween zinc chlo ide and zinc ni a e samples
a e bigge a 20°C ambien empe a u e as opposed o 25°C used in s udies [16‒18].
• The di e ence be ween induc ion pe iods and maximum empe a u es eached by cemen
samples wi h d ied and un ea ed zinc oxide was ela i ely small. Induc ion pe iod o bo h
samples we e simila wi h consis en di e ence be ween 5 o 7 h. Un ea ed zinc oxide
con ained 0.35 weigh % o wa e . This is insigni ican amoun ha p obably would no
in luence he esul s. The di e ence in hyd a ion induc ion pe iods was p obably caused by
di e en pa icle size dis ibu ion o hea ea ed and un ea ed zinc oxide and di e en le el
o homogeniza ion o sample pas es.
Acknowledgmen
This esea ch has been achie ed wi h he inancial suppo by he p ojec : GA19-16646S
“The elimina ion o he nega i e impac o zinc in Po land cemen by accele a ing conc e e
admix u es”, wi h inancial suppo om he Czech Science Founda ion.
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